Scattering lengths for collisions between sodium and potassium atoms

The scattering lengths that characterize the low-energy elastic scattering of Na-23 atoms by K-39, K-40 and K-41 atoms, when they interact via the X-1 Sigma(+) and a (3)Sigma(+), states of the NaK dimer, are calculated. The systematic variation of the short and long-range parts of the interaction potentials reveals that the calculated scattering lengths are sensitive to uncertainties in the potentials. It is concluded that precise spectroscopic measurements of the least-bound ro-vibrational levels supported by the ground electronic state, which would reduce the uncertainties in both the molecular potentials, are needed for an accurate determination of the scattering lengths.